This invention relates in general to viewers and deals more particularly with improved viewers for reading correlated data from a plurality of information sources.
Heretofore, method and apparatus have been provided to facilitate the reading of data from a plurality of related information sources wherein at least one of the sources comprises a transparency having data imprinted thereon. Systems of the aforedescribed type are useful for reading maps, charts and the like and may employ at least one transparent informaton source superimposed upon or arranged in overlying relation with another information source whereby the data on both information sources may be simultaneously viewed. Typical apparatus of the aforedescribed type is illustrated in U.S. Pat. No. 3,094,781 to Vangor for Course Finder, issued June 23, 1963. However, when one data source is superimposed upon another for simultaneously viewing confusion may occur, particularly if either or both of the information sources contain a substantial amount of data some of which is not of immediate interest to the viewer. A typical situation of this type is encountered in map reading where the reader is interested only in selected information as, for example, a route from a starting point to the destination. All other information on the map is of no immediate interest to the reader and may only serve to confuse him.
It is the general aim of the present invention to provide improved data reading viewers whereby selected data carried by a plurality of correlated information sources may be readily viewed to the exclusion of other data on the information sources, but not of immediate interest. The data reading viewers of the present invention facilitate map reading and may prove particularly useful in dispatching utility workers or the like to designated destinations. Detailed data relating to a destination, as for example, specific locations of utility lines at the destination, may be selectively viewed by the worker in relation to other pertinent data when the worker arrives at his assigned destination. However, it will be evident from the disclosure which follows that the method and viewer of the present invention may have other uses and may, for example, serve as a toy or be used as a teaching aid to permit questions and answers to be rapidly selectively viewed in relation to each other.